oras blob fetch failed to output to stdout in TTY mode

[qweeah]

What happened in your environment?

I tried to fetch a blob with oras blob fetch and output the content into stdout in terminal mode. The blob content is not printed to stdout as expected

➜  oras blob fetch ghcr.io/oras-project/oras@sha256:488a49baab43328b45444fc9c13861da4408f279ba5247569bbe06a732265fdc --output -
✓ Downloaded  application/octet-stream                                                                  167/167  B 100.00%     0s
  └─ sha256:488a49baab43328b45444fc9c13861da4408f279ba5247569bbe06a732265fdc

With --no-tty, the content can be printed

➜  oras blob fetch ghcr.io/oras-project/oras@sha256:488a49baab43328b45444fc9c13861da4408f279ba5247569bbe06a732265fdc --output - --no-tty
{"architecture":"unknown","os":"unknown","config":{},"rootfs":{"type":"layers","diff_ids":["sha256:31e4a5298aed7d277e1784bc57ff297a450e25eb59d5b7ac89f6bb229ac1a18a"]}}%

What did you expect to happen?

The blob content should be printed to stdout

How can we reproduce it?

Run below command

oras blob fetch ghcr.io/oras-project/oras@sha256:488a49baab43328b45444fc9c13861da4408f279ba5247569bbe06a732265fdc --output -

What is the version of your ORAS CLI?

v1.2.0-beta.1

What is your OS environment?

ubuntu 20.04

Are you willing to submit PRs to fix it?

• Yes, I am willing to fix it.

[FeynmanZhou]

To fix this issue, it would be reasonable to make --output - emit the content of "oras blob fetch" to stdout. That's being said, the flag --output - implies --no-tty in oras blob fetch. A sample experience is as follows:

$ oras blob fetch ghcr.io/oras-project/oras@sha256:488a49baab43328b45444fc9c13861da4408f279ba5247569bbe06a732265fdc --output -
{"architecture":"unknown","os":"unknown","config":{},"rootfs":{"type":"layers","diff_ids":["sha256:31e4a5298aed7d277e1784bc57ff297a450e25eb59d5b7ac89f6bb229ac1a18a"]}}%

[qweeah]

We should also allow user to avoid TTY resetting via explicitly put --no-tty=false.